Article Diaf2020 Article CharacterizationAndFrequencyAn(1)

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Applied Water Science (2020) 10:59
https://doi.org/10.1007/s13201-019-1132-4
REVIEW ARTICLE
Characterization andfrequency analysis ofooding solid ow
insemi‑arid zone: case ofMekerra catchment inthenorth‑west
ofAlgeria
M.Diaf1 · A.Hazzab1· A.Yahiaoui2· A.Belkendil3
Received: 20 December 2018 / Accepted: 23 December 2019 / Published online: 20 January 2020
© The Author(s) 2020
Abstract
In this study, we evaluate the soil erosion and solid transport in the oued Mekerra watershed in north-west Algeria. The
study area is subject to a semi-arid climate characterized by irregular rainfall and showers, which are often accompanied
by significant floods. These floods of large volumes transport large amounts of solid input to the Sarno dam, which is in
the outlet of oued Mekerra. Therefore, the water storage capacity of this dam is gradually decreasing, and it might reach
the volume of dead water. For this study, we utilized the hydrometric database provided by the National Agency of Water
Resources (ANRH). The operating period was 24years, from 1988 to 2012. This period was extended by classic regression
to 65years, which allowed extracting a series of annual maximum instantaneous flow rates (QIXA) and subsequently quanti-
fied the sediment yield during floods. The specific degradation mean created by the 11 floods was quite high, in the order
of 20tkm2year−1. The highest value of solid contribution was observed during the floods of October 2000 (250,000t), and
the value of liquid contribution was 7,151,608m3. The extracted results from the analysis of the graphs of concentration as a
function of the liquid flow (C = f′(Ql)) showed four types of hysteresis curves: clockwise loop, counterclockwise loop, shape
of eight, and straight line curve. Class II (clockwise loop) was the dominant class in the four events, namely the floods that
occurred on 09/22/1992, 09/21/1998, 09/27/1999, and the 08/24/2002. From these results, the water resource sector manag-
ers could formulate various methods for protection from floods and against the risk of sedimentation in storage structures.
Keywords Solid transport· Oued Mekerra· Semi-arid· Sediment concentration· Liquid flow
Introduction
Owing to its geographical location and climate regime,
Algeria remains severely limited in terms of water resources.
The volume of water lost by siltation in the dams is recog-
nized as one of the main problems of the country.
The phenomenon of loss of water is growing and threat-
ens more than 20 Algerian dams (Remini and Mokeddem
2018). The effect of erosion is not limited to the siltation of
dams, but it also deals with major problems such as degrada-
tion of fertile land, water quality, and the destabilization of
hydraulic structures.
The occurrence of flood is conditioned by the intensity
and quantity of the rainfall. The flow rate of each flood event
depends essentially on several hydrological and morphologi-
cal parameters, such as drainage density, slope, compactness
index, and the confluence ratio (Pallard etal. 2009; Yles and
Bouanani 2016). The high speed of the flow causes detach-
ment of soil particles from the bulk soil mass, which might
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s1320 1-019-1132-4) contains
supplementary material, which is available to authorized users.
* M. Diaf
[email protected]
A. Hazzab
[email protected]
A. Yahiaoui
[email protected]
A. Belkendil
[email protected]
1 Modeling andComputational Methods Laboratory,
University Dr. Moulay Tahar ofSaïda, P.O. Box138,
20000En-Nasr,Saïda, Algeria
2 Department ofCivil andHydraulic Engineering, Faculty
ofTechnology, University ofTahri Mohammed inBechar,
P.O. Box417, 08000Béchar, Algeria
3 Laboratory 60: Water Resources Valorisation, Science
andTechnology Faculty, University Abou-Bekr Belkaid
ofTlemcen, P.O.Box119, 13000Tlemcen, Algeria

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lead to transport of detached sediments (Hajigholizadeh
etal. 2018).
In Algeria, the specific erosion rate reaches consider-
able values, which exceeds 103tkm−2year−1. It reaches up
to 1120tkm−2year−1 in the High Tafna (Megnounif etal.
2004), 1330tkm−2year−1 in the Tafna sub-basin (Ghenim
etal. 2008), and 1875tkm−2year−1 in the Chelif sub-basin
(Meddi 1999). The watershed of the oued Mekerra con-
tributes to the siltation in the Sarno dam (commissioned in
1954), resulting in a significant amount of suspended solids
in the dam.
The main objective of the solid transport data analysis
is to determine the origin of the transported sediments,
through the analysis of concentration curves as a function
of flow rates (C = f(Q)). Several studies have focused on the
study of transport and quantification of solids (Nones 2019;
Mrokowska and Rowinski 2019; Di Francesco etal. 2016;
Tabarestani and Zarrati 2015; Vrolix and Pissart 1990). In
Algeria, several researchers have evaluated the sediment
transport associated with the floods in the country. A few
examples include the studies done for the watershed region
of the Tafna river in the north-west Algeria (Bouchelkia
etal. 2011; Ghenim etal. 2007; Megnounif etal. 2004; Ter-
fous etal. 2001) and for the region of Wahrane watershed
(Benkhaled and Remini 2003).
The diversity of relationships between liquid and solid
flows as a function of spatial and temporal disparity inter-
ested several researchers to carry out probability modelling
using frequency analysis for western Algeria (Yahiaoui and
Touaibia 2011), the eastern Algerian watersheds (Mouas and
Souag 2017), and the Walloon region of Belgium (Dautre-
bande etal. 2006). The hysteresis graph is one of the meth-
ods used to analyse sediment concentration as a function of
flow rates (C–Q) (Pagano etal. 2019; Sadeghi etal. 2018;
Zhao etal. 2017; Lloyd etal. 2016). Williams (1989) is
the first to categorize the hysteresis according to the shape
of each graph into five classes: clockwise loop, counter-
clockwise loop, eight loops, straight line, and complex
loop (Hamshaw etal. 2019). Hysteresis classes are used to
identify physical processes in the watersheds. For example,
clockwise hysteresis indicates that the source of sediment
could be the outlet of the watershed, while counterclockwise
loop hysteresis indicates that the source of sediments is in
the headwaters (Delaney etal. 2018; Chalov etal. 2017;
Baca 2008).
The dam of Sarno was built between 1947 and 1954 in
the outlet of the oued Mekerra watershed. At commission-
ing, it had a theoretical starting capacity of about 22Mm3.
oued Mekerra contributes to the silting of the dam of Sarno
by an average specific degradation of about 38tkm2year−1
(Cherif etal. 2017). To put forward a better strategy to fight
against this problem, it is necessary to have a precise under-
standing of the variations in the sedimentation rates during
each hydro-rainfall period. The determination on erosion
rate is based on the graphical analysis of the hysteresis
traced according to the relation Qs = f(Ql). The classifica-
tion proposed by Williams (1989) of the different loops of
hysteresis is adopted to determine the sources of origin of
the sediments.
Study area
The watershed of the oued Mekerra is a sub-basin of the
Macta watershed, mostly located in the Sidi-bel-Abbes
region in western Algeria. It is about 400km west of Algiers
(between 1°–0° 30′ W and 34° 20′–35° 15′ N). The basin
is limited to the north by the Tessala mountain range, to
the south by the highlands (Ras El Maa), to the east by the
Telagh plateau and the Saïda Mountains, and to the west by
the Tlemcen Mountains (Fig.1).
The main stream of oued Mekerra has its origin in the
high valleys; it drains an area of about 3000km2 and has a
course of 125km and an average slope of 5.5%, a perimeter
of 280km with a compactness coefficient of 1.43 that reflects
well the elongated shape of the watershed. The elevation of
mountain ranges is 1000–1100m in the north, 1200m in
the west, 1200–1260m in the south, and 870–1460m in the
east. 48% of the watershed is located above 1000 m above
sea level.
The oued Mekerra crosses two zones of very distinct
reliefs, the Daya mountainous massif in the south, with
an altitude between 800 and 1600m, and the plain of the
Mekerra, where the city of Sidi-bel-Abbes is located, in
the north, with an average altitude of 550m. The Mekerra
watershed is a result of drainage of several small streams and
tributaries. In the south, there are the El Kheoua, Sekhana,
El-Lellelah, Ras El Ouiden, and Farat Ezziet streams. In the
south-west are the Et-Touifza and Tadjmout streams and in
the north-west are the Lemtar, Bukhenafis, Anefress, and
Tissaf streams. All these streams contribute to the oued
Mekerra as the main stream in the catchment. It has its
source in the south at an altitude of 1100m and crosses
the city of Sidi-bel-Abbes at an average altitude of 500m,
with an average slope of about 1%. The vegetal cover in the
watershed is irregularly developed. Downstream from the
town of Ras El Ma appears Alfa covered land, which, to
the north, gives way to brush covered land. In the region of
Sidi Ali Benyoub, the Alfa gives way to cereals, vines, and
citrus fruits. About 20% of the basin area is forest-covered
(Otmane etal. 2018).
The following are some of the factors that favour the phe-
nomenon of erosion in the Mekerra region:
• A well-defined hydrographic network with a drainage
density of 1.67kmkm−2 and a torrential coefficient of

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Fig. 1 Geographical location of the oued Mekerra catchment

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0.23 indicates a torrential regime where the predomi-
nant soil erosion gives a very strong solid flow (Fig.2).
• The prolongation of the dry period during several
months has destroyed the plant cover that character-
izes as the main soil protector against the splash effect
(Benkhadra 1997).
• Only a part (20%) of the Macta watershed has forest
cover, consisting mainly of Aleppo pine and holm oak,
and hence provides a very weak protection against soil
erosion (Hallouche etal. 2017).
• The elongated shape of the watershed and the irregular-
ities in the rainfall and the vegetation cover are linked
to the fragility of the soil
Data acquisition
The climatological data for the period from 1990 to 2003
were provided by the National Agency for Hydraulic
Resources (ANRH). The climatology of the watershed
gives an average yearly rainfall of 300mm. During the
wet years, rainfall can reach up to 400mm, and during
dry years, it can decrease to less than 200mm (Fig.3).
The oued Mekerra catchment is under the influence of a
semi-arid Mediterranean climate characterized by a hot
and dry summer and a relatively mild and humid win-
ter. The prevailing winds are from the north-west and
west; the average maximum inter-annual velocity is about
20ms−1 (Otmane etal. 2018). The temperature values
vary between a minimum value of 10°C and a maximum
of 24°C, with an annual average of 17°C. The cold and
rainy period extends from the beginning of October until
the end of April, while the dry period starts from May
and last until September (Atallah etal. 2016). The evapo-
transpiration has an average value of 1670mmyear−1,
between a maximum of 1883mmyear−1 and a minimum
of 1588mmyear−1, resulting in the rapid drying up of
soils and the degradation of the vegetation cover. These
variations favour, in case of showers, the development of
a fast surface flow and significant erosion.
Fig. 2 Map of land cover of oued Mekerra catchment
Fig. 3 Rainfall variation (1990–2003)
Fig. 4 Correlation of maximum solid flow as a function of maximum
liquid flow rates

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The hydrometric series from the Sidi-bel-Abbes station
(station code—110301), which is located at the outlet of the
watershed (1° 00′–0° 30′ W; 34° 20′–35° 15′ N), extends
from January 1, 1988, to December 30, 2012, and includes
10,048 instantaneous data of liquid flow rates Ql (m3s−1),
solid flow rates Qs (kgs−1), concentration of suspended mat-
ter (gl−1), and heights (cm).
These data are recorded every 2days. During floods,
data survey is intensified up to 1h or even 30-min time
intervals depending on the flow level. However, this series
has missing data gaps for the years 1997, 2004, 2005, and
2007. These deficiencies are corrected by applying clas-
sical regression in the form of (Qs= aQl − b). The method
used is a numerical method based on the application of a
classical regression model with the hydrometric series of
(1988–2012). The law of regression is deduced with a cor-
relation coefficient of R = 0.87 (Fig.4). The series consid-
ered was extended for a 65-year period from 1943 to 2008.
Extension of the period of study is justified by the need for
continuous observation series over a sufficiently long period
(Vrolix and Pissart 1990).
The analysis of the variation of the maximum flows
between the years from 1943 to 2008 (Fig.5) gave two
dry periods that prolonged over the years 1947–1950 and
1955–1986. The other years were wet with the year 1994
recording 228m3s−1 of liquid flow and solid flow of
4030.86kgs−1, along with suspended matter concentration
of 20gl−1. The year 2008 recorded 183m3s−1 of liquid
flow and a significant solid flow of 3667.87kgs−1, which
confirms the irregularity of the flow rates in the basin.
The extreme flow of floods occurs twice a year, one during
autumn (October and September) with maximum value reach-
ing up to 200m3s−1 and another during spring, especially in
March and April, according to the cycles of annual flows from
the Sidi-bel-Abbes station. The torrential coefficient indicates
a torrential flow regime where soil erosion is predominant and
consequently a very strong solid flow. The stream flows in the
north of Algeria allow distinguishing two types of regimes: a
simple regime where the high waters occur in the cold season,
with a maximum between January and March, and the low
flows taking place in July–August. It characterizes the coastal
streams, and a complex regime with two annual maxima, more
or less marked, occurs in autumn and spring, the main low
water being in summer (Taibi etal. 1993); the latter character-
izes the flow in the stream of oued Mekerra.
Fig. 5 The variability of solid
flows and maximum liquid
flows from 1942 to 2008 at the
Sidi-bel-Abbes station
Table 1 The estimation of different solid–liquid contributions specific to the flood periods
P precipitation, H height, C concentration, QL liquid flow, Qs solid flow, AS solid input, AL liquid intake, ASS specific solid input
Date P (mm) H (cm) C (gl−1)QL (m3s−1)Qs (kgs−1)AS (103ton) AL (104m3)ASS (tkm−2)
18-Sept-89 15.12 292 30 33.24 997.2 29 110 10
10-Apr-92 50.3 274 10 25.36 253.6 5 66 1
22-Sept-92 02 296 33.4 35.12 1173 110 64 3
13-Nov-93 47 296 12.8 35.12 449.53 6 60 2
27-Aug-97 2.9 340 19.5 61.8 1205.1 45 299 15
16-Sept 97 46.7 385 21.9 120.5 2638.95 50 455 17
21-Sept-98 2.7 312 8.6 57.6 495.36 18 191 6
27-Sept-99 21.2 352 13.2 89.88 1186.46 47 309 16
24-Oct-00 64.2 421 65 161.8 10,517 250 715 83
24-Aug-02 46.4 392 17.6 127.13 2237.54 80 510 27
26-Oct-08 70.47 445 20 183 3667.86 120 1007 40
The mean 33.54 345.9 22.90 84.59 2256.50 6 344 20